Monitoring Via SNMP PRTG Manual

Monitoring via the Simple Network Management Protocol (SNMP) is the most basic method of gathering bandwidth and network usage data.

How SNMP Monitoring Works

SNMP is a set of standards for communication with devices in a Transmission Control Protocol (TCP)/IP network. SNMP monitoring is useful if you are responsible for servers and network devices such as hosts, routers, hubs, and switches. It enables you to keep an eye on network and bandwidth usage, and to monitor important metrics such as uptime and traffic levels.

You can use SNMP to monitor the bandwidth usage of routers and switches on a port-by-port basis, as well as device readings such as memory and CPU load. The target devices must support SNMP. Most devices with enabled SNMP require the same configuration (identical SNMP version and community string). To learn how to set up SNMP on a specific device, search the internet for its name and SNMP configuration.

Network Monitoring via SNMP

When you use a sensor with this technology, PRTG sends small data packets to a device, which in turn trigger reply packets. Compared to other bandwidth monitoring technologies via World Wide Name (WWN), packet sniffing, or Windows Management Instrumentation (WMI), the SNMP option creates the least CPU and network load.

Reasons to Choose SNMP Monitoring

SNMP is the most commonly used method because it requires minimal bandwidth and CPU cycles. If your network devices support SNMP and/or if you want to monitor large networks with several hundred or thousands of sensors, we recommend that you start with SNMP.

Besides network usage monitoring, another well-known feature of SNMP is the ability to also monitor other network parameters such as CPU load, disk usage, temperature, as well as many other readings, depending on the queried device.

SNMP Network Issues

To use SNMP for monitoring purposes, it is necessary that User Datagram Protocol (UDP) packets can be bidirectionally sent from the PRTG core server to the target device. This is usually the case in LANs and intranets. For connections across the internet, to a perimeter network (also known as DMZ, demilitarized zone, and screened subnet), or for WAN connections, some changes to the traversed firewalls might be necessary.

Keep in mind that SNMP v1 and v2c are no secure protocols, so you should not use them on the internet or with data connections that are not secure. Only SNMP v3 supports encryption.

Understanding SNMP Sensors

To better understand and set up SNMP sensors, you might want to learn more about the principles of object identifiers (OID) and Management Information Base (MIB) files.